摘要
双尖子山矿床位于大兴安岭南段,巴林左旗境内,是我国近年来新发现的一个超大型银多金属矿床。为了确定矿区内与矿体空间关系密切的蚀变斑岩与银多金属矿化在成因上的联系,及其物质来源特点,笔者等对其进行了锆石LA-ICP-MS U-Pb定年和Lu-Hf同位素的综合研究。结果表明,矿区内出露的近矿蚀变斑岩的形成时代为248.3±1.2 Ma,属早三叠世岩浆作用的产物。该岩体形成于银多金属矿化之前,在成因上与银多金属矿化并没有直接的联系。锆石原位Lu-Hf同位素分析结果表明,双尖子山矿区早三叠世蚀变斑岩的n(^(176)Hf)/n(^(177)Hf)值在0.282805~0.282993452之间,ε_(Hf)(t)值介于6.3~12.9之间。锆石Hf同位素二阶段模式年龄(T_(DM2))的峰值年龄集中在528 Ma到631 Ma之间,显示出亏损地幔或新生地壳来源的特征。
Objectives:The Shuangjianzishan deposit,which is located in the southern Great Hinggan Mountains,is a super-large silver polymetallic deposit newly discovered in Bairin Left Banner,Inner Mongolia,in recent years.The formation age,material source and its relationship with mineralization of the altered porphyry close to ore veins in the mining area have attracted the attention of previous scholars.Methods:A comprehensive study of single-grain zircon LA-ICP-MS U-Pb dating and Lu-Hf isotope was conducted for the altered granodiorite porphyry close to ore veins in this paper.Results:The results show that the altered granodiorite porphyry was formed at 248.3±1.2 Ma and is a product of Early Triassic magmatism.In situ zircon Lu-Hf isotope analysis shows that the n(^(176)Hf)/n(^(177)Hf)ratio andε_(Hf)(t)values of the Early Triassic granodiorite porphyry range from 0.282805 to 0.282993 and 6.3 to 12.9,respectively.The peak age of zircon Hf isotope two-stage model age(T_(DM2))is concentrated between 528 Ma and 631 Ma.Conclusions:The altered granodiorite porphyry close to ore veins intrusion was formed significantly earlier than mineralization,which also indicates that there is no direct genetic link between mineralization and Early Triassic magmatism.The intrusion was generated from depleted-mantle or juvenile-crust.
作者
王承洋
周永康
周智鸿
任云生
孙珍军
齐路晶
WANG Chengyang;ZHOU Yongkang;ZHOU Zhihong;REN Yunsheng;SUN Zhenjun;QI Lujing(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing,100037;College of Earth Sciences,Institute of Disaster Prevention,Sanhe,Hebei,065201;The No.104 Geological Team,Guizhou Provincial Bureau of Geology and Mineral Exploration,Duyun,Guizhou,558000)
出处
《地质论评》
CAS
CSCD
北大核心
2022年第3期863-876,共14页
Geological Review
基金
国家自然科学基金青年科学基金资助项目(编号:42002093)
中央高校基本科研业务费专题项目(编号:ZY20215134)的成果。
关键词
双尖山
近矿蚀变斑岩
锆石U-PB年代学
LU-HF同位素
地质意义
Shuangjianzishan
altered porphyry close to ore veins
zircon U-Pb geochronology
Lu-Hf isotope
geological significance
